2-Chloro-N-(3,5-dimethylphenyl)acetamide

The conformation of the C=O bond in the structure of the title compound, C10H12ClNO, is anti to the N—H bond and to the C—Cl bond in the side chain in all four independent molecules comprising the asymmetric unit. In the crystal, intermolecular N—H⋯O hydrogen bonds link the molecules into supramolecular chains

The conformation of the C O bond in the structure of the title compound, C 10 H 12 ClNO, is anti to the N-H bond and to the C-Cl bond in the side chain in all four independent molecules comprising the asymmetric unit. In the crystal, intermolecular N-HÁ Á ÁO hydrogen bonds link the molecules into supramolecular chains
C=O bond in (I) is anti to the N-H bond and to the C-Cl bond in the side chain ( Fig. 1), in all the four independent molecules comprising the asymmetric unit. This is consistent with the anti conformation of the C=O bond to the N-H bond and to the side chain methylene H-atoms in 2-chloro-N-(2,4-dimethylphenyl)acetamide (Gowda et al., 2008a), in 2-chloro-N-(3,5-dichlorophenyl)acetamide (Gowda et al., 2008b), and in 2-chloro-N-(3-methylphenyl)acetamide (Gowda et al., 2008c). The molecules in (I) are linked into infinite chains through intermolecular N-H···O hydrogen bonding (Table   1, Fig. 2). There are two independent supramolecular chains, one comprising O2-and O3-containing molecules, and the other comprising O1-and O4-containing molecules.

Experimental
Compound (I) was prepared according to the literature method (Shilpa and Gowda, 2007). Single crystals were obtained from the slow evaporation of an ethanolic solution of (I).

Refinement
The H atoms were positioned with idealized geometry using a riding model with C-H = 0.93-0.97 Å, N-H = 0.86 Å, and were refined with isotropic displacement parameters set to 1.2 times of the U eq of the parent atom. The structure was refined in the non-centrosymmetric space group Pna2 1 with four independent molecules in the asymmetric unit. No evidence for higher symmetry was found but the structure was refined as a racemic twin.
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.